The Common but Complicated Tool: Review of Embolic Materials for the Interventional Radiologist

Embolization is an important and widely utilized technique in interventional radiology. There are a variety of different categories and individual products which can be utilized to perform embolization. Understanding the different classes of embolic agents, the important features of each of these classes including strengths and limitations, and the variation in individual products within the classes is critical for interventional radiologist to practice safely and effectively. This article reviews the different kinds of embolics and relays some of the pertinent physical and chemical properties of individual products which should be considered when determining which embolic to select for a given purpose.

Urgent Transcatheter Arterial Embolization for Wunderlich Syndrome With Hypovolemic Shock Secondary to Ruptured Renal Angiomyolipoma

Purpose: Wunderlich syndrome (WS) with hypovolemic shock secondary to ruptured renal angiomyolipoma (rAML) represents an urgent condition. Hence, we reported our experience with transcatheter arterial embolization (TAE) using different embolic materials under this condition.Methods: This retrospective study consisted of 22 patients. Embolic materials including particles, microcoils, and liquid embolic agents were selectively used based on the decisions of interventional radiologists. Technical success was defined as the complete occlusion of bleeding vessels on the final renal angiogram. Clinical success was defined as the absence of re-hemorrhage needed for repeat endovascular or surgery treatment after TAE.Results: The articulated materials were used when WS presented without aneurysms; a combination of particulate materials and microcoils or Glubran 2 alone were used for WS with aneurysms. The technical success based on 24 episodes of TAEs in 22 patients was 100% (24 of 24). Repeat TAE was achieved in two patients with hemorrhages re-occurring two days after the initial embolization with microcoils alone. The clinical success was 90.9% (20 of 22). No nontarget embolization or embolization-related complications occurred during the TAE procedure. Of the patients, 27.3% (6 of 22) experienced minor complications of post-embolization syndrome (PES). During a median follow-up time of 34 months, no recurrent hemorrhage that required repeat endovascular or surgical treatment for hemostasis occurred.Conclusion: Urgent TAE with the selective use of different embolic materials is an effective alternative to control WS with hypovolemic shock secondary to ruptured rAML. The condition of presenting with or without aneurysms may determine the embolic materials employed.

Analysis of outcomes of endovascular embolisation: A cross-sectional two-center study on 46 visceral artery pseudoaneurysms

Purpose Visceral artery pseudoaneurysms (VAPAs) are uncommon in clinical practice but may have serious clinical outcomes up to death. Endovascular management is a safe effective alternative option to traditional surgical procedures. This study assesses the outcome of different embolic materials and techniques used in the endovascular management of VAPAs. Materials and methods This is a two-center retrospective analysis of endovascular embolisation of 46 VAPAs, with a mean pseudoaneurysm size of 13 ± 11.35 mm, that were urgently managed between July 2018 and March 2020. Patients’ presentations were GIT hemorrhage, intrabdominal hemorrhage, hematuria, and abdominal pain in 34.78%, 30.43%, 23.91%, and 10.87% respectively. Management using coils only was done in 28/46 patients (60.87%), NBCA glue only in 16/46 patients (34.78%), combined coils and NBCA glue in 1/46 patient (2.17%), and Amplatzer plugs only in 1 patient (2.17%). The management techniques were sac packing in 9/46 patients (19.57%), inflow occlusion in 28/46 patients (60.87%) and trapping in 9/46 patients (19.57%). All patients were followed-up for 1 year after the procedure. Results The overall clinical success and periprocedural complication rates were 93.48%, and 15.22% respectively, and 30-day mortality was zero. Clinical success was 92.86% in the coil subgroup (n = 28), and 93.75% in the NBCA glue subgroup (n = 16). The technical success rate was 100%. Effectiveness of the procedures during the follow-up was 97.83%. Target lesion re-intervention rate was 2.17%. Conclusion Transarterial embolisation can provide high technical and clinical success rates with low periprocedural complication and re-intervention rates, as well as satisfactory procedure effectiveness in the management of VAPAs.

Comparison of three embolic materials at partial splenic artery embolization for hypersplenism: clinical, laboratory, and radiological outcomes

Purpose To compare effectiveness of three widely used embolic agents in partial splenic embolization (PSE) by analyzing their clinical, laboratory, and radiological outcomes within one year of follow-up. Materials and methods This retrospective study examined 179 patients who underwent PSE to manage hypersplenism secondary to cirrhosis. Patients were divided into 3 groups according to embolic agent used. Group 1 (gelatin sponge) included 65 patients, group 2 (embospheres) included 58 patients, and group 3 (PVA) included 56 patients. Clinical, laboratory, and radiological outcomes were compared between groups. Results The technical success rate was 100% in all groups. Pain as a major complication was lower in the gelatin sponge group (20%) compared to the embosphere group (31%) and PVA group (32.3%). Major complications other than pain were found in 20.1%; 24.6% in gelatin sponge group, 15.5% in embosphere group and 19.6% in PVA group (p = 0.045). WBCs and platelet counts showed a significant increase after PSE in all groups. Entire splenic volume as measured by computed tomography after PSE showed no significant difference among the 3 groups; however, the volume of infarcted spleen was significantly lower in the gelatin sponge group compared to other two groups (p = 0.001). The splenic span was significantly reduced one-year post-procedure in three groups (p = 0.006), and it was significantly less in embosphere and PVA groups compared to gelatin sponge group (p < 0.05). Recurrent bleeding was higher in gelatin sponge group (p < 0.05). Conclusions Permanent embolic materials achieved better laboratory and radiological outcomes than gelatin sponge particles in PSE of cirrhotic hypersplenism patients. However, permanent particles were associated with greater abdominal pain.

Transvenous Pressure Monitoring Guides Endovascular Treatment of Vein of Galen Malformation: A Technical Note

<b><i>Introduction:</i></b> Vein of Galen malformations (VGMs) are complex congenital arteriovenous malformations that generally require serial endovascular treatment sessions to slowly correct the high-flow fistulous connections that cause increased venous pressures and ultimately lead to the classic presentations of heart failure, hydrocephalus, and intracranial hemorrhages. Despite the advances in endovascular technology and embolic materials, the resolution of embolization is often limited to the subjective view of diminished flow on angiograms. <b><i>Case Report:</i></b> An 8-month-old patient with a VGM developed clinical signs of heart failure and growing head circumference with ventriculomegaly. The patient was treated endovascularly with a transvenous approach for coil embolization while undergoing continuous monitoring of the post-malformation venous pressures. The arterial and venous systolic blood pressures (SBP) were collected at serial time points and used to measure estimated 95% confidence interval bounds for arteriovenous SBP gradients and determine when sufficient coil embolization and flow reduction was thought to be achieved. <b><i>Conclusion:</i></b> The transvenous pressure monitoring demonstrated progressively increasing pressure gradients between the arterial and venous systems that correlated with the degree of flow reduction on angiographic runs. The patient underwent successful coil embolization of the VGM and had improvement of heart failure and ventricular size in follow-up at 8-month post-op. This provides a novel technique to introduce an objective measurement that can guide the embolization of a VGM.

Endovascular balloon-assisted liquid embolisation of soft tissue vascular malformations: technical feasibility and safety

Purpose Arteriovenous malformations (AVMs) are abnormal communications between arteries and veins without an intervening capillary system. The best endovascular treatment option for these is unclear and may involve multiple staged procedures using a variety of embolic materials. We report our initial experience using a modified version of a previously published neurointerventional technique to treat soft tissue AVMs with single-stage curative intent. Materials and methods Soft tissue AVMs treated endovascularly using either sole arterial or combined arterial and venous balloon-assisted techniques with liquid embolic agents were retrospectively identified over a 3.5 year period (January 2017 to June 2020)) at two centres. Clinical, pre-operative radiological, procedural technical and post treatment details were recorded. Results Seven patients were treated for symptomatic soft tissue arteriovenous malformations. These AVMs were located in the peripheral limbs (five), tongue (one) and uterus (one). Curative treatment was achieved in 6/7 patients with one patient requiring a second treatment approximately 1 year later. A variety of liquid embolisation agents (LEAs) including sclerosants and polymers were used. Clinical success rate was 100% following treatment. One patient experienced expected temporary post-operative tongue swelling requiring tracheostomy occurred following embolisation of the lingual AVM. A minor complication in a second patient was due to an access site haematoma developed following treatment of the hand AVM requiring surgical intervention. No long-term sequelae or additional complications were observed. Conclusion Endovascular arterial and venous balloon assisted LEA embolization of soft tissue AVMs with curative intent is feasible. This technique may provide an alternative treatment option for achieving durable occlusion for complex soft tissue AVMs.

Endovascular management of vascular renal injuries: outcomes and comparison between traumatic and iatrogenic settings

Purpose: To evaluate the efficacy of endovascular treatment for vascular renal injuries (VRIs) like bleeding, pseudoaneurysm and artero-venous fistula (AVF) and to compare patients with blunt trauma (T-VRIs) with those with iatrogenic damage (I-VRIs). Methods: We retrospectively assessed 49 renal artery embolizations performed to treat T-VRIs (26.5%) and I-VRIs (73.5%). Different embolic materials were used based on the type of lesion. Technical success was defined as the complete occlusion of target arteries with no further visualization of VRIs. Clinical success was defined if no recurrence was present and if renal function (difference between creatinine after and before treatment <0.5 mg/dl) was preserved after 1 month. Results: Angiography showed bleeding in 27 patients, pseudoaneurysm in 29 and an AVF in 6. Embolic agents used were coils in 39 procedures, coils with sponge in four and others in six. Technical success was 100% while clinical success was 85.7% due to seven patients with recurrence. The group I-VRIs showed a higher rate of clinical success than the group T-VRIs (94.4% vs 61.5%; p < 0.05). Moreover, the group I-VRIs had a higher incidence of pseudoaneurysms and AVFs compared with the group T-VRIs (69.4% vs 30.8% and 16.7% vs 0%; p < 0.05). Conclusion: Endovascular treatment for VRIs showed satisfactory results and no patient had a worsening of renal function. I-VRIs had better clinical success and more frequently appeared as pseudoaneurysms compared to T-VRIs: probably iatrogenic injury is localized and pseudoaneurysm is easily identifiable and treatable with endovascular treatment.

Treatment of carotid cavernous sinus fistulas with flow diverters. A case report and systematic review

Introduction Carotid cavernous fistulas (CCFs) are rare, usually follow head trauma or aneurysmal rupture. Recent treatment options include endovascular techniques such as flow diversion devices (FDDs). Objective To present our case treated with FDD application with transarterial cavernous-sinus coiling and present a systematic review on the use and effectiveness of FDDs in CCF treatment. Materials and methods We present our case of CCF treatment with FDD. A search was also conducted in PubMed, EMBASE and Cochrane until November 2020. Reference lists were also cross-checked. Results Including our case, thirty-eight patients were identified with a CCF that was treated with FDDs in sixteen studies. Twenty-two patients were females, nine were males and the rest unidentified. The mean age was 52,6 years (range 17–86, SD± 19.28). Thirty-six patients suffered from direct and two from indirect CCFs. Single FDD was used in four cases, single FDD with embolic materials in eleven cases, multiple overlapping FDDs were used in six cases and multiple overlapping FDDs with embolic materials were used in seventeen cases. Thirty-five patients (92,1%) had clinical improvement, immediate angiographic occlusion was seen in 44,7% of the cases, while long-term occlusion rate was 100% but with variable follow-up periods. One patient (2,6%) presented with a neurological deficit related to FDD deployment. Conclusion Targeted treatment of CCFs with single or overlapping FDDs with or without adjunct embolic agents offers a high success rate, both clinically and long-term angiographically compared to other endovascular methods alone. However, further research with multi-center prospective trials is warranted.